In this context, a special set of logistical requirements interacts with a wide variety of technical and cost constraints, to pose technical challenges for effective or optimal solutions. The ever-increasing size and weight of individual blades adds to these challenges. In general, it may be said that after their construction, wind turbine blades undergo a series of handling and storage stages from their production site to their installation location. These stages may include initial storage at a production site, transportation from a production site to an installation site or to an interim storage or marshalling site. There may be further transportation between one or more interim storage or marshalling sites to an installation site. Each interim storage stage may include transferring steps in which blades are lifted off a first transportation platform and on to another. Storage and handling solutions are sometimes optimised for individual stages of the transition between production and installation. To that end, there may be provided a whole range of support or storage solutions, each individually configured for a particular storage or transport stage and requiring repeated switching between different storage or transport structures. This is costly, time-consuming and can increase the tendency to inflict damage or wear on blades. There can be many advantages arising from devising a blade handling solution which facilitates multiple stages of the transportation process as a whole, including interim storage stages.
The present invention seeks to provide an effective wind turbine blade transport and handling solution which addresses the needs to ensure damage-free transportation of the blades, quick handling during transfers whether between transport platforms or between storage and transportation stages, as well as safety and ease of use by personnel. In aspects, special consideration has been given towards secure transportation of on- or offshore blades by shipping.
Wind turbine blade support and transportation devices are known in which a frame element is applied at a blade root while another co-operating frame element is provided outboard of a blade root region, often in a mid- or tip region. These may be referred to as root- and tip frames respectively. In some cases, these may be stackable thereby allowing several blades to be supported lying more or less horizontal or slightly inclined, and stacked atop one another. For example, WO2015149809 discloses a stackable frame arrangement in which the tip- and root frame each allows a lateral tilting of a respective root or tip support element, thereby accommodating a possible height difference between the level of the tip frame and the level of the root frame. That document also discloses a root frame which has a pivot action. The root is secured to the frame by an attachment means having tubular structures for receiving stud bolts in the blade root face. EP2708731 recites stackable blade frames in which a root support member is supported by a root frame. The root support member is rotatable about a blade lengthwise axis. Moreover, the root support member is connectable to a blade root via tubular sleeves which co-operate with stud bolts projecting from the root face. In EP2796709, an alternative arrangement is shown allowing a root frame, fixed to a blade root, to be rotated when a tip clamp at the blade tip is separated from a tip frame. The tip and root storage fittings can be accommodated in respective transport frames at an angle offset by approximately ninety degrees to the storage orientation. Moreover, that document also discloses a blade root transport frame with attachment plates. Bolts can be passed through these plates into threaded holes in a blade root in which no stud-bolts are present, thereby securing the frame to a blade root. EP2418376 discloses a wind turbine blade transport frame for a blade root, the frame having fixed bars with through holes for fixing to a blade root.
The present invention sets out to provide improvements to known blade frames.